The correctly punctuated sentence is: "In 2019 eight new students enrolled in our school, but only five of them stayed."
However, it should be noted that there is a minor punctuation error in that sentence as well. It should include a comma after "2019": "In 2019, eight new students enrolled in our school, but only five of them stayed."
If you are looking specifically for the sentence that does not require any adjustments for punctuation, then the first sentence, "After driving all day and night, we finally reached our destination, and we happily went to sleep.", is correct as it stands.
So, the final answer could be either "After driving all day and night, we finally reached our destination, and we happily went to sleep." or "In 2019, eight new students enrolled in our school, but only five of them stayed." with the adjustment for the latter.